Anode activity in vacuum arc plays a very important role in both characteristics of vacuum arc and the interruption capacity of vacuum interrupters. In this paper, the transient thermal processes of anode in vacuum arc in a half of arc current cycle with frequency of 50 Hz are simulated by finite element analysis software, ANSYS. Some important phenomena of anode, e.g., the melt and solidification, mass loss due to evaporation, are investigated.